Study on contrast response and detecting performance of machine vision system

This paper preliminarily investigates the performance of machine vision system from the perspective of contrast and object detection process. We set up a testing system using a lightbox, transmissive/reflective test charts, a photometer, and two cameras. The photometer was used to obtain the standard luminance of the test chart. First, we obtain the DN response characteristics for luminance of two cameras with different dynamic ranges (72 dB and 123.6 dB). Based on this result the relationship between luminance domain and camera domain contrast ratio is provided. Distribution of the signal and contrast in the camera domain under low luminance conditions show the advantage of 16bit camera over 8bit camera. To link the camera's performance in practical scene, we conducted imaging tests of reflective resolution targets under various illuminance levels. We observed that the contrast and imaging quality of resolution targets by the camera at critical states can help establish correlation between single-metrics and scene-based imaging recognition performance evaluation.